We have a new scanning LiDAR system that will be used for repeating the previous Laser Altimetry Project profiles. The main components are a Riegl LMS-Q240i scanning laser altimeter, an Oxford Technical Solutions Inertial+2 inertial measurement unit (IMU), a Trimble R7 geodetic GPS receiver, and a small form factor PC (from Cappuccino PC) for data logging. 

The Riegl scanner has a 60 degree beam sweep, range up to 650 meters, and measures 10,000 data points per second. The IMU measures the aircraft attitude (pitch, roll, yaw, and rates about those axes) and several other measurements, all at 100 times per second. The Trimble GPS records raw, dual frequency data which is post-processed (after the survey) against similar data recorded at a fixed GPS basestation to provide precise positioning of the aircraft. At typical speeds/heights for the aircraft we use, we will collect data on a roughly 1m X 1m grid along a 500m wide swath.

The design philosophy of this system keeps everything as compact and complete as possible in a single package. Cabling and connections to the rest of the aircraft are kept to an absolute minimum: Only power-in (12 VDC, 8 amps) and three GPS antenna cables are needed. Pilot and Instrument Operator display information (height above ground, data quality, recording on/off) is output via simple html over ethernet. Total system weight is approximately 22 kg (50 lbs).

The system will be fit to two aircraft, a Cessna 185 (in a Alaska Skycraft bellypod) and a Texas Turbines converted DHC-3 Otter.

All three companies (Riegl, OxTS, Trimble) offered their products at generous discounts for research/educational use, and all have provided excellent equipment and top-notch technical support. Funding for this system comes from the Director's Office of the Geophysical Institute, NASA's Earth Science Project Office, and NSF's Arctic Natural Sciences Program.